Cache Tag Invalidation for Proxy Hops
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Solution Overview
Problem
In content delivery platforms, invalidating stale cached content objects across multiple proxy hops is non-trivial, error-prone, and difficult due to their widespread distribution across different data centers, requiring complex manual coordination and management.
Innovation Solution
Implementing a cache tagging mechanism that uses cache tags with expiration timestamps, where a default cache tag can be overridden for a specified period, ensuring that stale cached copies are evicted before reverting back to the default, thus simplifying cache invalidation across proxy hops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual coordination is used to invalidate cached content objects across multiple proxy hops, then cache invalidation can be performed, but the process becomes error-prone, difficult, and time-consuming
Solution Approach 1:
The patent introduces cache tags as an intermediary mechanism that mediates between the content source and multiple proxy hops. The cache tag is attached to the content object and propagated through the cache hierarchy, automatically invalidating cached copies at all proxy hops without requiring manual coordination. This intermediary tag system resolves the contradiction by making the invalidation process reliable while eliminating coordination complexity.
Solution Approach 2:
The cache invalidation system enables self-service through automatic propagation of invalidation signals. When a cache tag is updated or expired, the invalidation automatically propagates through the cache hierarchy without human intervention. Each proxy hop independently processes the invalidation based on the cache tag information, making the system self-managing and eliminating error-prone manual coordination.
2Extent of automation
If cache tags with override expiration are implemented, then automatic cache invalidation is achieved, but the cache tagging mechanism complexity increases
Solution Approach 1:
The patent uses parameter changes in the form of cache tag versions and expiration timestamps to automate cache invalidation. By changing the cache tag parameter (version number) or setting an expiration timestamp, the system automatically triggers invalidation of stale cached objects. This approach achieves high automation by using simple parameter modifications rather than complex invalidation logic, resolving the contradiction between automation extent and mechanism complexity.
Data Source
AI summary
One or more computing devices, systems, and/or methods for content cache invalidation using cache tags are provided. A first proxy hop may receive a request from a client device for a content object originating from a content source. A cache tagging script is executed to add a query parameter to the request to create a modified request. The query parameter specifies a cache tag version for the content object. The modified request is transmitted through one or more subsequent proxy hops to the content source to retrieve the content object. The content object, tagged with a cache tag specifying the cache tag version, is cached as a cached content object within a cache. The cache tag is associated with an expiration timestamp after which the cached content object is designated to be invalid.